31 August 2005

Warning for the squeamish and youngsters: this series of posts will have photographs and descriptions of a dead bird in various stages of decomposition.

Days 4 & 8

On day 4 (day 0 and days 2 and 3), the feeding frenzy had begun. There were many blow fly (Calliphoridae) maggots on and around the bird. After I opened the lid, several of them climbed up the sides and left. The bird’s skull was partially visible. The strong odor was very offensive.

I suspect the smaller maggots (yellow arrows) are younger than the larger maggots (orange arrow), although the smaller ones could belong to a different species. The picture below is a more enlarged look at both types of maggots. A small maggot is visible near the upper left hand corner.

After this climactic day, I did not check on the bird again until day 8. By then, all the flesh and skin had been consumed and only the bones and feathers were left. There were no maggots, but only a few ants. A microscopic examination would probably have revealed smaller arthropods feeding on the remnants, but I didn’t feel like bringing indoors the container, which still had an unpleasant, but much weakened, odor. If I ever repeat this experiment, I may consider setting up a microscope outdoors.

I will now attempt to recover and clean the bones of the bird in hopes of having a complete catbird skeleton.

The repulsiveness of maggots notwithstanding, did you know that the use of blow fly maggots is a medically accepted therapy for debriding (cleaning) infected and gangrenous wounds?

30 August 2005

Warning for the squeamish and youngsters: this series of posts will have photographs and descriptions of a dead bird in various stages of decomposition.

Days 2 & 3

On day 2 (two days after I found the dead bird―day 0 is here), there were several flies trapped inside the box. I had punched holes thru the walls of the box to let the flies in, but once inside the box they were apparently having difficulty locating the holes to get back out.

These are blow flies (family Calliphoridae). They can detect the smell of a dead animal from far away. Female blowflies deposit their eggs on carcasses. After I opened the lid I also saw many ants crawling on the bird. I also noticed that the bird had started to smell (day time temperatures had been up to about 33°C). But, otherwise, it still looked intact.

On day 3, there were more flies and ants on and around the bird, the appearance of which had changed since the previous day. There were many loose small feathers around and the tail feathers had fanned out, indicating that the skin and the flesh had been breaking down.

The bird also smelled stronger than before and the odor was similar to that of rotting fish. This is the smell of various amines that are probably produced when proteins are breaking down.

29 August 2005

Warning for the squeamish and youngsters: this series of posts will have photographs and descriptions of a dead bird in various stages of decomposition.

Day 0

Dead things don’t go to Heaven or Hell. They rot, get eaten and turn into soil. Life goes on. Many organisms have evolved to obtain their nourishment solely from dead animals or plants. In nature, nothing goes to waste and nothing lasts forever. A dead tree may take decades to finally turn into soil, but, as this series of posts will show, a small dead animal left out in the open when the weather is warm and humid will be bare bones in a matter of a few days.

One thing that interested me a lot during my teenage years was how organic matter decomposed. But far from being a morbid fascination, this was a purely scientific interest. Back then, my knowledge of science was still quite rudimentary and naive and, unfortunately, I did not have access to good scientific books or teachers. To satisfy my curiosity, I mostly asked questions to myself and did simple experiments (and took notes, some of which still survive). One of my experiments involved the sealing of an entire apple in a jar full of water to see how long it would take to rot.

So when I ran into a dead bird on the sidewalk on 31 July, I figured it was a perfect chance to rekindle my interest in this subject. But, no, I didn’t bring the bird home under my hat. Unfortunately, plastic bags are perennially littering the landscape and fortunately, there happened to be one nearby.

Once in the backyard, I quickly photographed and examined the bird, which, I believe, was a gray catbird (Dumetella carolinensis). Its neck appeared to have been broken, but it had no external injuries as far as I could see. The condition of the body and the lack of any smell indicated that it had died, perhaps, not more than an hour or so earlier.

Next, I put the bird in a plastic box with holes punched thru its lid, bottom and side walls. Then I placed the box in a secluded corner of the yard and secured its lid with a couple of large rocks. The last measure is necessary to prevent backyard body snatchers (raccoons, etc.) from gaining access to the body.

27 August 2005

It must have occurred to others too that any particular configuration of clouds that one notices in the sky has never existed before and that the configuration will quickly change, especially on a windy day, and will never exist again1.

So what profound philosophical implications might this revelation have? I haven't the slightest idea.

1. The total number of possible distinct configurations of clouds there can be would be an enormous number if it could be meaningfully calculated. Consequently, assuming that cloud patterns develop more or less randomly, the probability of any one of them forming twice during the lifespan of our universe must be nil for all practical purposes.

26 August 2005

Late yesterday afternoon I was on a walk in nearby woods when this butterfly showed up and landed on my hat. I got my camera ready, took off my hat, but the butterfly flew away. I put my hat back on and the butterfly came back and landed on it again. This went on several times. It must have been a funny sight. Finally, I took off the hat and held it in front of me, the butterfly returned and I snapped a picture of it.

I believe it is one of the anglewings (genus Polygonia). I wonder what was attracting it to my hat.

25 August 2005

Following along the lines of my recent posts on miniaturization of animals (here and here), I am putting up these pictures of a tiny snail, Vertigo gouldi, an endemic of North America. The shell of this particular adult individual was 1.6 mm long.

This species was named by Amos Binney in 1843 after Augustus A. Gould (1805-1866), an early American malacologist. Binney’s drawing from his 1857 classic the Terrestrial Air-breathing Mollusks of the United States is on the right. As you can also see in the photograph below, the shell is covered by fine striae, a characteristic that helps distinguish this species from other closely related ones.

The genus Vertigo is in the family Vertiginidae (or the Pupillidae, depending on who you believe). One notable characteristic of this genus and a few other related genera is that the snails have only one pair of tentacles. All other pulmonate land snails that carry their eyes on the tips of their tentacles (order Stylommatophora) have two pairs of tentacles, one longer upper pair and a shorter lower pair. The Vertiginidae lack the latter pair as you can see in the photograph of the live snail.

Both photographs of Vertigo gouldi were taken with an Olympus Camedia C-5000 digital camera through an Olympus SZ60 stereomicroscope.

23 August 2005

In the first entry in this series, I introduced some general concepts from the literature. If this were a manuscript intended for publication, at this point I would give examples of some of the smallest known animals, but I haven’t finished compiling my list. So, instead I am skipping ahead to a discussion of the limits to minimum size.

Rensch1 discussed one potential factor that may limit how small an animal can get.

...the eggs set a lower limit to body size because their size cannot be reduced ad libitum. This fact seems to be the reason why there is only one ripe egg at a time in the smallest Gastrotricha and Rotatoria, in the minute snail Caecum glabrum, and apparently also in the smallest frog Phyllobates limbatus. There are other such minute types of terrestrial snails, such as Punctum pygmaeum, Pyramidula rupestris, and species of Vallonia and Vertigo, in which only one or two eggs will ripen simultaneously and the smallest cyprinodont, Heterandriaformosa, usually gives birth to only a very few young at short intervals.

Of course, the largest mammals and the largest birds also tend to produce one offspring at a time, but possibly for other reasons.

What Rensch means by egg dimension being a lower limit to body size is that as animals get smaller, the masses (or sizes) of their eggs relative to the adult masses (or sizes) tend to get larger2. An example of this relationship is provided by the change in the ratio of the egg mass to the adult mass in birds as a function of adult mass.

Data were from Table 3-1 in Calder2.

This negative relationship between adult size and relative egg mass arises, because below a certain size eggs would not be viable, perhaps because there wouldn’t be enough room for both the embryo and its food inside the egg. One way to get around this problem would be to have the tiny eggs growing inside the body of a host other than that of the mother. In other words, very small embryos would have to be parasitic and derive some or all of their nutrition from outside the egg.

I have carried out a similar analysis with land snails by substituting linear dimensions for masses3.

Data were from Table 12-1 in Heller4.

Based on this, I tentatively conclude that the rapid increase in relative egg size as a snail gets smaller is one factor that limits the miniaturization of land snails.

1. Rensch, B. 1959. Evolution above the species level. Columbia University Press.2. W.A. Calder 1996. Size, function, and life history. Dover Publications.3. The tiniest snail eggs would be difficult to weigh, because they are so small and adult snails are difficult to weigh, because they normally contain large amounts of free water in their mantle cavities. I have taken into account only those species with roughly spherical eggs.4. Heller, J. (2001) in The Biology of Terrestrial Molluscs, Edited by G.M. Barker. CABI Publishing.

20 August 2005

The well-known Monty Python skit (here and here) about a restaurant where every dish contains Spam and most items on the menu are along lines of "spam, egg, spam, spam, bacon, and spam" or "spam, bacon, sausage, and spam" has a lesser known real life equivalent.

The members of Major Long's Expedition to the Rocky Mountains, including the zoologist Thomas Say, spent the winter of 1819-1820 at Engineer Cantonment where their usual fare, if they were lucky, was fresh venison, otherwise, "salt pork of a very inferior quality"1. On 25 February 1820, Say and his party were invited to dinner at nearby Camp Missouri. The dinner menu, according to Weiss and Ziegler1, consisted of "the entire bison hump, the rump of the bison roasted, boiled bison meat, two boiled bison tongues, the spinous processes roasted in the manner of spare-ribs, sausages made of minced tenderloin and fat, etc., together with excellent bread, and coffee".

In referring to this menu, Say commented that they had been so long without vegetables that they were not missed.

19 August 2005

This beer comes from the Otter Creek Brewing Company in Vermont. It is a dark ale with a nice aroma and a light bitter after taste. According to the label it "complements any hearty meal". It certainly went well with the rather odd assortment of stuffed grape leaves, roasted red peppers, some sort of cheese (the label had been discarded), hot salsa and whole wheat crackers I had for lunch today (more on these peculiar food combinations of mine in the future).

According to the Otter Creek website this beer "tastes great with chocolate". I must try that next time. But, why is it called Stovepipe?

18 August 2005

Sometimes I am asked why I study animals so unimportant to human life and economy as pseudoscorpions. There is one simple answer: every aspect of nature that interests the human mind is worthy of study whether or not it is of direct importance to man.Peter Weygoldt, The Biology of Pseudoscorpions

Pseudoscorpions' large claws (pedipalps) make them look like scorpions, but they lack the true scorpions' stings and are usually much smaller than the latter. The specimen pictured above, about 3 mm long, was one of the largest I have seen. Some species of pseudoscorpions do have poison glands, but these open near the tips of their pedipalps1.

Pseudoscorpions are quite common in soil, but because most species are only a few millimeters in length, they usually escape attention. The only time I come across them is when I am sorting through forest soil samples for tiny snails.

Pseudoscorpions are predators that feed on other small arthropods. They also have a peculiar behavior of attaching themselves to the bodies of larger arthropods, for example, flies, and allowing themselves to be transported in this fashion. This is known as phoresy. Phoresy presumably helps the pseudoscorpions to become dispersed over large areas1.

17 August 2005

Dear Nicholas,I received your letter today announcing my nomination as an "International Scientist of the Year". Me, a scientist of the year? Thank you, thank you. I am speechless. Is this an honor or what? I have a feeling I am gonna be hearing from the Nobel Committee next.

I am indeed honored to be considered worthy of this esteemed award invented by your venerable center, excuse me, centre1. And all this for practically nothing. All I have to do is send you a check for $370 (or provide you with my credit card number) in return for a lousy "pictorial testimonial" with my name and picture on it. I might even consider adding to my order an "Official Gold Gilt Medal of Excellence" for another $370. You really know how to spoil a scientist.

How can I ever thank you enough? Is there something else I can do, besides revealing my credit card number to you, to express my gratitude? But, here is an idea. Why don't you send me a check (or cash, which I'd prefer) for $400 (sorry, things are a bit more expensive on this side of the Atlantic). And I will mail to you with express mail, I promise, a full-color certificate to commemorate the nomination of your little ploy as the Most Idiotic International Scam of the Year 2005.

He had a boy-like love of sweets, unluckily for himself, since he was constantly forbidden to take them...He drank very little wine, but enjoyed, and was revived by, the little he did drink. [p. 96]

Latterly he gave up dinner, and had a simple tea at half-past seven (while we had dinner), with an egg or a small piece of meat. [p. 100]

Much earlier, Charles Darwin himself had written about his culinary experiences while traveling on the Beagle2.

September 17th. [1833, Tapalguen on the way to Buenos Aires] We were here able to buy some biscuit. I had now been several days without tasting anything besides meat: I did not at all dislike this new regimen; but I felt as if it would only have agreed with me with hard exercise.

[1834, the Strait of Magellan] There is one vegetable production deserving notice from its importance as an article of food to the Fuegians. It is a globular, bright-yellow fungus, which grows in vast numbers on the beech-trees. When young it is elastic and turgid, with a smooth surface; but when mature, it shrinks, becomes tougher, and has its entire surface deeply pitted or honeycombed, as represented in the figure at right...In Tierra del Fuego the fungus in its tough and mature state is collected in large quantities by the women and children, and is eaten un-cooked. It has a mucilaginous, slightly sweet taste, with a faint smell like that of a mushroom.

October 8th. [1835, James Island, the Galapagos] While staying in this upper region, we lived entirely upon tortoise-meat: the breast-plate roasted (as the Gauchos do carne con cuero), with the flesh on it, is very good; and the young tortoises make excellent soup; but otherwise the meat to my taste is indifferent.

16 August 2005

If you are ever in the Ft. Myers area in Florida, leave some time aside to visit the J.N. “Ding” Darling National Wildlife Refuge on Sanibel Island. And when you are at the Refuge, instead of driving around, I recommend that you hike the approximately 4-mile Indigo trail if you want to see more of the wildlife. I did the hike last July on a very hot day, but it was worth it.

I noticed that the birds were usually tamer than the same or the related species I had seen elsewhere. The great egret (Ardea alba, left) and the little blue heron (Egretta caerulea, right) would rather keep their eyes on the things moving in the water than on a tourist with a camera. Even the red-shouldered hawk (Buteo lineatus, below, left) let me approach the tree it was perched on before it flew away.

The snowy egret (Egretta thula, above, right) too tolerated me for a few shots (with the camera) before it took off trailing its yellow feet behind.

15 August 2005

Last Sunday Stephanie Clark and I were down at the Potomac River. Yesterday, we explored the 10-Mile Creek area in Black Hill Regional Park in Boyds, Maryland. The sinistral Physa that we had found around the Potomac a week earlier were very abundant in the small shallow pools alongside the 10-Mile Creek.

The snail1 on the left was crawling on the bottom of the pool. You can see its long skinny tentacles out in front of the shell. These snails do not have gills, but obtain oxygen through a highly vascularized section of the mantle cavity, which is their “lung”. Hence, they, and their terrestrial relatives, are called “pulmonate” snails. The lung opens to the outside through a hole known as the “pneumostome” or simply, the breathing hole.

To breathe, Physa come to the surface of the water every now and then and bring the pneumostome in contact with air. So, if you sit by one of these pools and start paying attention to what’s inside, you will soon notice that there is a constant traffic of snails, sometimes two or three attached to each other’s shells, moving up and down between the bottom and the surface. It's an amusing sight. The picture on the right above shows one snail that was floating upside down at the surface.

Later during our hike through the woods, the trail passed over a tiny stream imperceptibly flowing down to the lake below us. We walked up the stream to its spring, which was nothing more than a muddy spot among the trees. While Stephanie took out her sieve to search for aquatic creatures, I took out my camera to go after a moth I had spotted. A few minutes later, she called out to me: “I’ve found bivalves!” In utter disbelief, I responded: “Bivalves? There is hardly any water here.” Expecting a large clam, I opened my hand and Stephanie put a speck on my finger. Sure enough, it was a bivalve.

This is a Pisidium (family Sphaeriidae). Some species grow bigger, but this one on the tip of my finger, possibly an adult, was barely 2 mm across.

13 August 2005

In June 2004, a few days before departing for Turkey for a land snail expedition, I picked up George Bean's classic Aegean Turkey. I had planned field trips on the mountains between Izmir and Manisa (ancient Magnesia) and wanted to get an idea of what ancient stuff we might run into besides snail shells. Rather than well-known ruins of Greek cities that are the favorites of ordinary tourists, I was more interested in isolated, largely forgotten bits and fragments of history and Bean had a generous list of those along with photographs or drawings. One such site, actually a natural rock formation said to resemble a sorrowful woman, Niobe to be exact, was supposed to be on Mt. Sipylus at the outskirts of Manisa.

In Greek mythology Niobe was Tantalus's daughter. After she insulted goddess Leto by bragging over the fact that she had 14 children, while Leto only two, the latter sent her children, Artemis and Apollo, to kill those of Niobe, which they did. Upon seeing this, horrified Niobe escaped to Mt. Sipylus where she turned into stone and a stream formed from her tears.

Bean tells us that until the late 1930s, a rock carving east of Manisa had been identified as Niobe1, before H. T. Bossert located a large rock in the shape of a woman's head closer to Manisa and concluded that it matched the ancient descriptions better.

A couple of weeks later, having finished our snail survey of Mt. Sipylus, we were driving down the mountain to Manisa when we spotted some limestone outcrops at the far end of what appeared to be a crude parking lot alongside the road. We decided to stop and look for snails for the last time―even though the stop before this one had meant to be the last one. A trail alongside a cliff led us to a deep ravine at the bottom of which was a feeble stream barely flowing towards the ruins of an old watermill. About 20 minutes later we were walking back to the car with a bag of snail shells and I had just finished entering the GPS coordinates into my notebook when I looked up ahead of me. Suddenly, one of the photographs I had seen in Bean flashed before my eyes. There was no mistaking it, it was Niobe in front of me, still recognizable after all these thousands of years and still sorrowful2.

Click for a larger picture. Manisa is in the background. The "theater" in the foreground is a modern eyesore.

1. Some apparently still associate Niobe with this carving.2. An account of another traveler's visit to the site of Niobe is here.

12 August 2005

Cyrus Harding1, dipping in his hand, felt the water oily to the touch. He tasted it and found it rather sweet. As to its temperature, that he estimated at ninety-five degrees Fahrenheit2. Herbert having asked on what he based this calculation,―

"Its [sic]3quite simple, my boy," said he, "for, in plunging my hand into the water, I felt no sensation either of heat or cold. Therefore it has the same temperature as the human body, which is about ninety-five degrees."Jules Verne, The Mysterious Island

The National Weather Service is predicting that today the air temperature will go up to about 36° C (96° F) around Washington, DC. So, by Jules Verne's logic, it should feel just right and quite comfortable outside. Which is, of course, total nonsense.

Thermodynamically, no chemical process can be 100% efficient. As a result, all metabolic activities produce heat, which is what humans and all other animals use to warm up their bodies. However, because humans cannot turn off their metabolism, heat is always generated and the excess must be dissipated to the surroundings to prevent the body from overheating above the normal temperature of about 36.7° C.

Whenever a body is at a higher temperature than its surroundings, the rate at which energy is lost to the surroundings in the form of heat is proportional to the temperature difference between the body and the surroundings. In other words, as the temperature of the body approaches that of the surroundings, less and less heat is transferred to the surroundings. And that is why when the ambient temperature is near the normal body temperature, rather than feel comfortable, we feel hot, because our bodies begin to overheat.

The situation is slightly different in water, because water is more efficient than air in conducting heat. That is why being in water at 36° C feels more comfortable than being in air at 36° C. Nevertheless, when you put your hand in water at 36° C it feels warm. Believe me, because I tried it last night. I filled up a sink with water while adjusting the temperature to about 36° C by turning the hot and cold water faucets on and off. When I put my hand in it, it felt warm, not "neutral". My wife, who voluntereed as an unbiased subject (she didn't know what the temperature was), also reported that the water was warm.

I can't forgive Verne for not having the common sense to test his idea before putting it in his book. Maybe he didn't have a thermometer.

1. Some editions, for example the French text at Gutenberg, give this name as Cyrus Smith.2. The French text gives the temperature as “quatre-vingt-quinze degrés Fahrenheit (35 degrés centigrades au-dessus de zéro)”.3. It should, of course, be “It’s”. This simple error is present both in my paperback copy and in the Gutenberg e-text.

11 August 2005

If you look in any decent book on seashells, you will come across the genera Littoraria and Littorina in the family Littorinidae (commonly known as periwinkles). Although considered to be "seashells" or marine snails, some species in these genera spend almost all of their adult lives on land.

The snail pictured above, Littoraria angulifera, is common in mangrove forests in Florida. I photographed this one on a mangrove branch about 3 meters above the ground near Sanibel Island last July.

These snails appear to be the end of a lineage of marine gastropods that couldn't quite complete their evolution from marine to terrestrial life. For example, they breathe air even though they have gills; their activities are regulated by both the rain and the tides.

Their most vital connection to the sea not only reveals where they originated, but also explains why they can't move away from it: they must return to the sea to release their eggs.

As you can imagine, these snails offer many important clues to the transition of life from the sea to the land. I will return to them in the future.

10 August 2005

This week’s book in the bag is the Polish malacologist Andrzej Wiktor’s1 The Slugs of Greece, volume VIII in the Fauna Graeciae series, published in 2001. I had ordered a copy from Backhuys Publishers back in the Spring and it arrived a couple of weeks ago. The cost, including shipping, was almost 50 Euros, or $66.50.

I am primarily interested in the slugs of Turkey. However, I bought this book for two reasons. First, I suspect that Greece and Turkey share some of their slug species, especially those that live along the western Mediterranean coasts of Turkey and the adjacent Greek islands and those in the Thrace. Second, no comparable monograph on the slugs of Turkey has yet been published.

The book is, fortunately, in English and it is well illustrated. Drawings of preserved specimens and of genitalia are given for almost all the species recorded from Greece. There are distribution maps, an index of all the generic and specific names mentioned in the book and a short essay on the zoogeography of the slugs of Greece. If you are too interested in the slugs of Greece and Turkey I recommend this book.

Okay, now the shortcomings of the book. It would be good to have at least one figure in the book that labeled the individual parts of the genitalia. I am familiar enough with slug anatomy to figure out what is what, but a novice would be very confused by all the unlabeled drawings. Ideally, good color pictures of live slugs would be much more preferable to black and white drawings of preserved specimens. Understandably, however, a book with color photos would have been too costly to produce given the fact that the production of this book as it is was already delayed for about 6 years for “economic reasons”. As the author indicates, this unfortunate delay in production resulted in some of the taxonomic information being obsolete when the book finally came out.

What is also obsolete is Wiktor’s paleogeographic basis for the zoogeography of the Aegean area. For this, Wiktor seems to rely on a 1943 paper2. This was long before our current, and still incomplete, understanding of the paleogeography of the Aegean Sea, based on plate tectonics, was developed. Another event that Wiktor doesn’t consider, but which might also have influenced the dispersal, not only of slugs, but of most other animals, was the drying of the Mediterranean Sea about 5 million years ago.

The biogeography of the Aegean Sea area offers many puzzles and challenges. Much more work needs to be done before we have a better understanding of how evolution shaped the animal and plant faunas into what they are today. Wiktor’s book will be a good starting point for all future work.

1. A Polish colleague instructed me that, for those of us ignorant of Polish, a good enough phonetic spelling of this name would be “Andjey Viktor".2. The full citation for this paper (“Jeannel 1943”) along with a few other works cited in the text are not included in the list of references at the end of the book.

09 August 2005

Many scientists routinely put full-text copies of at least some their publications on their homepages (while others inexplicably don’t). Below is a very limited list of such sites where you can download published papers. The coverage of this list is obviously biased towards my interests. I will sporadically provide updates as I discover new sites.

Please note that scientists move around and some of these link may in time become obsolete. If a link is not functional, try moving up the URL to a more general address or search the Internet for the scientist’s name.

08 August 2005

Australian malacologist Stephanie Clark, who was famous for more than 15 minutes back in May for rediscovering in Alabama a snail (Clappia cahabensis) that was presumed extinct (here and here), is working in D.C. this month. Yesterday, I took her out on a field trip along the C&O Canal and the Potomac River. We had an almost 5-mile hike on the canal’s towpath that included frequent stops to photograph the abundant butterflies and wading trips into the Potomac to search for snails. The butterfly above is a red admiral (Vanessa atalanta). There were many others, but I will save their pictures for another post.

Here is Stephanie standing in the Potomac while trying to teach me about freshwater snails. (Yes, we did get our pants wet.)

Stephanie’s favorite freshwater snail genus is Physa. The picture below shows two of them that Stephanie pulled out from the murky bottom of the river. If you look carefully, you will notice that the coiling direction of their shells is sinistral. In a previous post, I wrote about the coiling directions of snail shells and indicated that the shells of most snail species are dextral. But, in Physa, the normal coiling direction is sinistral.

Stephanie and I are planning another field trip for next weekend. Look for the results of that trip here next Monday.

06 August 2005

Around here, sidewalks are good places to find dead insects (and earthworms). The only problem is I usually run into interesting things when I don't have a container with me. But, I have discovered that insects transported on my head under my hat normally arrive home intact.

While out jogging today, I found not one, but two sidewalk casualties, one dragon fly and one cicada, and brought them home, the usual way, under my hat.

As for earthworms, no, I haven't considered carrying them on my head (yet).

05 August 2005

I found this skin of a cicada nymph on a signpost yesterday. Such empty skins left behind by insect nymphs have always intrigued me. The skins usually preserve the external organization of the larvae—from the minute hairs to the bulging transparent eyes—perfectly.

For several years I have kept a cicada skin similar to this one on my desk. Sometimes I cannot help but wonder whether, if I touched it gently, it would start crawling among the clutter on my desk. But a large slit on its back gives its secret away. This is the slit through which life escaped, carried away by the adult insect in its new cells. What is left is an organization of dead cells. If we could scrutinize the insides of the remaining cells we would see that the molecular organization that was once responsible for life, the primary structure of the organism, is now destroyed, although the various organs and other structures formed by the cells, the secondary structure, and the overall organization of the organism, the tertiary structure, are still mostly intact, at least in their external appearances.

The adult insect that came out of the skin on the post was probably one of the annual species the nymphs of which emerge from the soil every summer. If it hasn't been eaten by a bird yet, it is probably somewhere on a tree now trying to ensure that at least some of its genes will live on.

1. These ideas are in part from a paper I published many years ago: Örstan, A. 1990. How to define life: a hierarchical approach. Perspectives in Biology and Medicine, 33:391-401.

04 August 2005

Last Saturday afternoon, while gardening in the backyard I noticed this small fly (~ 7 mm long) sitting motionless near the tip of a stalk of buds about a half a meter above the ground. I quickly got my camera and took some pictures of it. Its eyes, so big relative to the overall dimensions of its body, attracted my attention. It looked like it was keeping an eye on everything around it, including myself. What else would it do with such oversized eyes? Luckily, it ignored me and the camera and stayed where it was. After I finished with picture taking, I walked away to another corner of the garden.

About five minutes later when I returned, it was still there. But I noticed that there was now a small object attached to the front of its head where its mouth would be. So I got the camera back out and took another series of pictures of it. The fly stayed at its perch for a long time with the small object that appeared to be a tiny insect hanging in front of its mouth. The fly didn’t appear to be eating it, for its mouthparts weren't making any noticeable motions and the prey wasn't getting any smaller as far as I could tell.

Later, after I downloaded the pictures to my computer and enlarged them on the screen, I saw that the fly had its proboscis inserted into its victim's body and was obviously sucking up its insides.

This was a robber fly* (family Asilidae). A week ago Nuthatch had a post on these predators of other insects over at bootstrap analysis.

The small yellow organ visible just below its wing, near the junction of the thorax and the abdomen is, if I'm not mistaken, one of the halteres (there is another one symmetrically located on the other side of the body). The halteres are believed to help maintain equilibrium during flight.

*Note added 7 August: Giff Beaton kindly responded to my e-mail inquiry to identify the genus of the fly in the picture as Cerotainia.

More information on robber flies and pictures are available at these sites:

02 August 2005

This is the first entry in what I hope will be a series of posts on the subject of miniaturization in animals, specifically in land snails.

I am writing these partly to organize my own thinking, so the content may get technical at times. Also, if this were a paper intended for publication (it actually is, but not yet), I would start out by giving examples of the tiniest animals. But, the nice thing about writing for the Internet is that I can start anywhere I want and post what I’ve written in any order I want. I will revise and reorganize as I go along.

The subject of miniaturization brings 2 broad questions to my mind:1. What are the evolutionary processes that favor and result in miniaturization of animals?2. What are the consequences of miniaturization?Tied in with the last question are additional ones. What are the limits to miniaturization? Or, in other words, what is the smallest animal that has evolved and can theoretically evolve? Also, can one species become very small and still retain the morphological and physiological characteristics of larger species?

Rensch1, early in the 1950s reviewed the then available evidence on the genetics of body size and concluded that “body size is brought about by single genes in some cases and by several genes in others”. This is probably true, but then, he continued with the following statement:

Nevertheless, body size must invariably be considered as a single character in processes of selection, and if this character is favored, a large number of morphological, anatomical, histological, physiological, and developmental relations will be changed in the process.

I have to do some more thinking to understand what he exactly meant by this and to decide whether I agree with him or not.

Regarding the anatomical changes that accompany miniaturization, Rensch1, also offered the following generalization: “In approaching the lower size limit of phylogeny, the organisms usually reduce special structures and special organs and only the indispensable mechanisms are maintained.”

Hanken & Wake2 further developed this idea. From their review, I have extracted following 3 possible evolutionary consequences of miniaturization in animals:

1. Underdevelopment or loss of organs.2. Variation in the presence/absence of an organ.3. Morphological novelties.

There are numerous examples of underdevelopment or loss of organs and related variation in miniature land snails. I will present examples and continue this discussion in a future post.

01 August 2005

I have a long commute to and from work. On a good day, when the trains are running on time, it's about 1 h and 10 min each way; otherwise, longer. I make the best of my time by reading or taking naps.

I carry a big bag for my lunch, notebook, various odds and ends, and, of course, for the books, magazines or the journal articles that I may be reading on a given day.

Here is this week's reading material in the bag.

Peter Atkins is Professor of Chemistry at Oxford University. One of his earlier books, Creation Revisited, remains as one of my most favorite books. Galileo’s Finger, published in 2003, has chapters dealing with evolution, DNA, energy, entropy, atoms, quantum mechanics and cosmology; in other words, just about everything in the universe. Although I am more or less familiar with most of the subject matter, I am enjoying the book, mostly because of the snippets of wisdom Dr. Atkins extracts from his analyses of natural phenomena and reveals to us here and there in the book.

For example:

The really immortal component of life is not the physical gene, it is the abstract information it contains. Information is immortal, and information is ruthlessly selfish. Genetic information is probably the ultimate unit of selection, with DNA its realization and a body its discardable, subservient vessel.

I am not sure if I agree that genes (or their information content) are the units of selection, but this is still a thought-provoking idea.

In fact, the two great foundations of science are casuality, the influence of one event on a subsequent event, and energy. Casuality is essentially the coherence and consistency of the chain of commands that keeps the universe moving and which we disentangle to achieve understanding; energy is the ever watchful guardian of propriety, ensuring that causality causes only legitimate actions.

Why, of course, why didn’t I think of that before?

Creationism, including its transparently camouflaged variant “intelligent design”, is not science: it is an untestable assertion pursuing and impelled by an anti-science, religiously motivated agenda.

That really sums it up.

Also in the bag is the issue No. 34 of the Zoology in the Middle East that arrived last week. As its title implies, this journal is devoted entirely to zoological studies carried in Middle Eastern countries, which, by the publishers’ definition, also include Armenia. Some of the articles in this issue are on the bats of Turkey, gekkos of Egypt, new records of fishes from the Gulf of Aqaba and earthworms of Jordan.

One interesting note is about the brown bears (Ursus arctos) in Golestan National Park in Iran that eat sunflower seeds growing in farms adjacent to the park. The authors (Khaleghizadeh & Khormali) are recommending that the farmers be compensated for the damage caused by the bears “before farmers consider to kill the bears”.

ZME is published by Kasparek Verlag and the subscription price for two annual issues is 48 Euros. They accept credit card payments, so there is no need to waste time and additional money with bank transfers or postal money orders.

Last but not least, I am reading the July issue of the monthly Turkish magazine Toplumsal Tarih. This magazine, published by the Tarih Vakfi, is mostly about the history and archaeology of Turkey with occasional articles on other regions of the world. Many articles concern lesser known historical events or persons or some forgotten historical aspect of Turkish culture. I have had difficulty coming up with an appropriate English title. Perhaps, I would call it “Societal History”. It is a pretty good publication; arguably the best of its kind published in Turkey. Nevertheless, the writing needs to be refined quite a bit. They need better writers or editors to clean up the grammar and simplify the style.

In the July issue there are articles on the remains of the Byzantine hippodrome in Istanbul, a 1586 shipwreck off Amasra on the Black Sea coast of Turkey, the coal mines in Zonguldak and the Yezidis in Turkey.

I subscribed to Toplumsal Tarih last January through Tulumba (“the largest Turkish Megastore in the USA”). The issues have been coming regulary all the way from Turkey via Tulumba in New York. The subsciption costs $36 for 6 issues.